APPARATUS AND METHOD FOR THE POST-PROCESSING OF SEQUENTIALLY PRINTED SHEETS

Abstract

An apparatus and method for the post-processing of successively following, sequentially printed sheets, includes a conveyor, a folding table, a folding sword, a folding roller pair, at least one pressing-down mechanism, and a machine control that is operatively connected to the folding sword and the pressing-down mechanism. The pressing-down mechanism includes at least one mechanical braking element which acts in the region of the back edge onto the top side of the printed sheet to be positioned on the folding table. The stationary folding sword includes a compressed-air device with at least one outlet opening for compressed air which is focused onto a folding roller gap. The folding table forms a gathering device for at least two successively following printed sheets. A sensor, arranged in a region of the conveyor, is operatively connected to the machine control and functions to detect the printed sheets, transported with the conveyor.

Claims

1. An apparatus for the post-processing of successively following, sequentially printed sheets, comprising a conveyor for transporting printed sheets in a conveying direction; a folding table, arranged in a downstream region of the conveyor, for accommodating the printed sheets, the folding table constructed and arranged as a gathering device for at least two successively following printed sheets; a folding sword arranged at a vertical distance to the folding table, wherein the folding sword is arranged to be stationary and comprises a compressed-air device that is connectable to a first compressed air source and has at least one outlet opening a folding roller pair with an in-between arranged folding roller gap, the roller pair being arranged on a side of a folding table that is opposite a side on which the folding sword is located, wherein the outlet opening of the compressed air device is focused on the folding roller gap for introducing compressed air to fold the printed sheets; at least one pressing-down mechanism, positioned above the folding table and in an upstream region of the folding table, for pressing down in the direction of the folding table a back edge of a printed sheet to be positioned on the folding table, wherein a front edge of a following printed sheet is supplied while raised up relative to the back edge of the printed sheet positioned on the folding table; and wherein the at least one pressing down mechanism includes at least one mechanical braking element for the printed sheets which acts upon a top side of at least one printed sheet to be positioned on the folding table; a machine control operatively connected to the folding sword and the at least one pressing-down mechanism; and at least one sensor arranged in a region of the conveyor which cooperates with the machine control for detecting the printed sheets conveyed with the conveyor.

2. The apparatus according to claim 1, comprising an end stop arranged in a region of the folding table for stopping front edges of printed sheets gathered on the folding table.

3. The apparatus according to claim 2, wherein the end stop is movable in and counter to the conveying direction of the printed sheets.

4. The apparatus according to claim 1, wherein the at least one pressing-down mechanism is connectable to one of the first compressed-air source or a second compress-air source and includes at least one exit opening for compressed air which is focused onto a top side of a respective printed sheet to be positioned on the folding table, in a region of a back edge of the respective printed sheet.

5. The apparatus according to claim 4, wherein the at least one mechanical braking element is arranged between the at least one exit opening of the pressing-down mechanism and the folding table.

6. The apparatus according to claim 1, comprising at least two separate pressing-down mechanisms which are respectively arranged transverse to the conveying direction for the printed sheets at a distance to a side from an upstream end of the compressed-air device for the folding sword.

7. The apparatus according to claim 6, wherein the distance to the side of the at least two separate pressing-down mechanisms is adjustable.

8. The apparatus according to one of the claims 1, wherein the folding sword comprises a plurality of segments arranged successively in the conveying direction.

9. The apparatus according to claim 1, wherein the conveyor comprises a lower belt and an upper belt cooperating with the lower belt for transport of the printed sheets.

10. The apparatus according to claim 9, wherein the lower belt and the upper belt extend into a region of the folding table.

11. The apparatus according to claim 10, wherein the lower belt and/or the upper belt are arranged to converge toward each other in the region of the folding table.

12. The apparatus according to claim 1, further including at least two sensors in a region of the conveyor, wherein the at least two sensors are operatively connected to the machine control for detecting the printed sheets transported by the conveyor and are arranged spaced-apart transverse to the conveying direction.

13. The apparatus according to claim 1, wherein the folding roller pair and the folding sword are arranged in one of a longitudinal direction of the conveying direction or a cross direction to the conveying direction.

14. The apparatus according to claim 1, wherein the folding roller gap has a gap width that is adjustable.

15. A method for post-processing of successively following, sequentially printed sheets, comprising: transporting by a conveyor the successively following, sequentially printed sheets in a conveying direction to a folding table arranged in a downstream region of the conveyor; depositing the transported printed sheets on the folding table; operating jointly for folding the printed sheets a folding sword positioned at a vertical distance to the folding table and a folding roller pair with an in-between formed folding gap positioned on a side of the folding table that is located opposite the folding sword, wherein the folding sword is stationary and includes at least one outlet opening for blowing compressed air; pressing down a back edge of a preceding printed sheet to be positioned on the folding table with at least one pressing-down mechanism in a direction of the folding table for braking the preceding printed sheet, wherein the pressing down mechanism includes a mechanical braking element making contact with a top side of the preceding printed sheet in a region of a back edge of the preceding printed sheet; supplying a following printed sheet with a front edge of the following printed sheet raised up, relative to the back edge of the preceding printed sheet positioned on the folding table; controlling the pressing-down mechanism and the folding sword via a machine control; gathering at least two successively following printed sheets on a gathering device of the folding table to form a joint stack; folding the joint stack into a print product by compressed air from a first compressed-air source blown onto the joint stack through the at least one outlet opening in the stationary folding sword; detecting a printed sheet transported with the conveyor by a sensor which is operatively connected to the machine control; computing with the machine control corresponding control signals based on information obtained from the sensor for pressing down the back edge of the preceding printed sheet with the pressing down mechanism for braking the printed sheet by the mechanical braking element and for triggering activation of the folding sword for carrying out the folding step; and triggering the pressing down, braking, and folding with the control signals.

16. The method according to claim 15, comprising conveying the front edges of the printed sheets to be gathered on the folding table against an end stop arranged in a region of the folding table.

17. The method according to claim 16, comprising displacing the end stop either in or counter to the conveying direction for the printed sheets in when there is a changed format for the printed sheets to be gathered on the folding table.

18. The method according to claim 15, comprising supplying the at least one pressing-down mechanism with compressed air from the first compressed-air source or from a second compressed-air source; wherein the pressing down step includes blowing out the compressed air through at least one exit opening of the pressing-down mechanism in a region of the back edge and onto the top side of the printed sheets to be positioned on the folding table.

19. The method according to claim 15, wherein the pressing down includes conducting the compressed air blowing out of at least one exit opening of the pressing-down mechanism onto the at least one mechanical braking element to deflect the at least one mechanical braking element in the direction of the folding table and bringing the at least one mechanical braking element into contact with the printed sheet to be positioned on the folding table or to be supplied to the joint stack.

20. The method according to claim 15, wherein the pressing down includes blowing the compressed air out via at least two separate pressing-down mechanisms which are respectively arranged transverse to the conveying direction for the printed sheets at a distance to a side from an upstream end of a compressed-air device of the folding sword.

21. The method according to claim 20, comprising correspondingly reducing or increasing the side distance of the at least two separate pressing-down mechanisms for a following order to process printed sheets having a smaller or larger format, respectively.

22. The method according to claim 15, comprising: introducing the compressed air supplied by the first compressed-air source into a plurality of segments of the folding sword, arranged successively in the conveying direction; and admitting, under control of the machine control, compressed air to only the segments of the folding sword positioned in a region of the joint stack.

23. The method according to claim 15, comprising transporting the printed sheets to the folding table in a conveying gap formed between a lower belt and an upper belt of the conveyor.

24. The method according to claim 23, comprising transporting the printed sheets with aid of the lower belt and the upper belt of the conveyor into a region of the folding table.

25. The method according to claim 24, wherein the lower belt and the upper belt converge toward each other and further comprising guiding the printed sheets in the region of the folding table between the converging lower belt and/or the upper belt.

26. The method according to claim 15, comprising detecting the printed sheets in the region of the conveyor with aid of at least two spaced-apart sensors arranged transverse to the conveying direction and operatively connected to the machine control.

27. The method according to claim 15, wherein the folding includes folding the joint stack in a longitudinal or cross direction to the conveying direction of the printed sheets transported with the conveyor.

28. The method according to claim 15, comprising correspondingly adjusting a gap width of the folding roller gap for a following processing order with different thickness of the joint stack to be folded.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0036] In the following, the invention is described in further detail together with accompanying drawings, with the aid of exemplary embodiments, wherein:

[0037] FIG. 1 is schematic view from the side of an inventive apparatus for the post-processing of printed sheets according to a first exemplary embodiment;

[0038] FIG. 2 is a simplified schematic view from the front of the inventive apparatus according to the first exemplary embodiment, shown counter to the conveying direction for the printed sheets; and

[0039] FIG. 3 is a schematic view from the side of an inventive apparatus for the post-processing of printed sheets according to a second exemplary embodiment.

DETAILED DESCRIPTION OF THE INVENTION

[0040] FIG. 1 shows in a first exemplary embodiment a schematic view from the side of an inventive apparatus 1 for the post-processing of printed sheets 2.sub.1 . . . n, printed sequentially with a non-depicted digital printing press. A shown, the printed sheets 2.sub.1 . . . n can be non-folded, folded once, or folded several times and can be supplied to the apparatus 1 in a random sequence. The apparatus 1 comprises a conveyor 3 for transporting the printed sheets 2.sub.1 . . . n, here the printed sheets 2.sub.4, 2.sub.5, 2.sub.6 and 2.sub.n, in a conveying direction 4. The machine also comprises a folding table 6 arranged in a downstream region 5 of the conveyor 3, a folding sword 7 arranged above the folding table 6 in a central position and transverse to the conveying direction 4, as well as a folding roller pair 8 arranged below the folding table 6 and comprising a first folding roller 9 and parallel thereto a second folding roller 10. The folding sword 7 is here provided with and is mounted on a height-adjustable holding element 7 (FIG. 2). Of course, the folding sword 7 can also be arranged below the folding table 6 and the folding roller pair 8 correspondingly arranged above the folding table if necessary. In general, the folding sword 7 is thus arranged at a vertical distance to the folding table 6 and the folding roller pair 8 is also positioned at a vertical distance to the folding table 6, but on the side opposite the folding sword 7.

[0041] The conveyor 3 is composed of a lower belt 11, consisting of several individual belt sections, arranged parallel and spaced-apart transverse to the transporting direction, which are not shown herein, as well as an upper belt 12, extending parallel thereto and operating jointly with the lover belt 11, wherein a conveying gap 13 for the printed sheets 2.sub.1 . . . n formed between these belts. The lower belt 11 as well as the upper belt 12 extend into the region of the folding table 6. Of course, the lower belt 11 and the upper belt 12 can also be embodied converging toward each other in that region, so that a continuously narrowing conveying gap 13 results in the region of the folding table 6 (FIG. 3).

[0042] The folding sword 7 is embodied stationary and comprises a compressed-air device 15 that is connected to a first compressed-air source 14, with several s 17 (FIG. 1), which are arranged sequentially in conveying direction 4 and are supplied separately with compressed air 16. Each segment 17 comprises at least one outlet opening 18 for the compressed air 16, which is directed toward the folding table 6.

[0043] The folding table 6 forms a gathering device 6 for successively arriving printed sheets 2.sub.1 . . . n. An end stop 19 that can be adjusted to the format of the printed sheets 2.sub.1 . . . n is arranged in the region of the folding table 6 for the front edges 2.sub.1 . . . n, of the gathered printed sheets 2.sub.1 . . . n resting on the folding table 6, the printed sheets 2.sub.1, 2.sub.2 and 2.sub.3 in this case. For this, the end stop 19 is connected to a first adjusting device 20.

[0044] Referring further to FIG. 2, the two folding rollers 9, 10 are respectively provided with a rotational axis 9, 10, oriented parallel or nearly parallel to each other and parallel to the folding table 6. The folding rollers 9, 10 are positioned on opposite ends 21, 22, respectively in separate bearing locations 23, 24 (FIG. 2). They are arranged spaced-apart and transverse to the conveying direction 4 and thus have a folding roller gap 25 between them for accommodating and further moving the printed sheets 2.sub.1 . . . n to be folded. The orientation of the rotational axes 9, 10 of the folding rollers 9, 10, relative to each other, and thus also the folding roller gap 25 that forms can be varied, depending on the thickness of the printed sheets 2.sub.1 . . . n gathered and resting on the folding table 6, meaning corresponding to the folding pattern used and/or the type of paper used. The folding table 6 has a recess 6 above the folding roller gap 25 through which the printed sheets 2.sub.1 . . . n to be folded can pass. The folding rollers 9, 10 are furthermore driven counter-rotating, relative to each other, and are connected to a drive motor 26 (FIG. 1). Finally, a second adjusting device 27 for changing the spacing between the folding rollers 9, 10 is arranged on both sides at the bearing locations 23, 24 for the folding rollers 9, 10, which serves to adjust the folding roller gap 25 and/or its gap width 25. As an alternative, the bearing locations 23, 24 can also be spring operated.

[0045] Referring further to FIG. 3, to press down one back edge 2.sub.1 . . . n of a printed sheet 2.sub.1 . . . n to be positioned on the folding table 6 in the direction of the folding table 6, several pressing-down mechanisms 29 are arranged spaced apart in conveying direction 4 above the folding table 6, in its upstream region 28. The pressing-down mechanisms 29 are furthermore arranged transverse to the conveying direction 4 of the printed sheets 2.sub.1 . . . n, at a side distance 30 to an upstream end 15 of the compressed air device 15 for the folding sword 7. This side distance 30 can be adjusted via a third adjusting device 31, indicated only by double arrow herein (FIG. 2). The pressing-down mechanisms 29 are connected to a second compressed-air source 14 and are respectively provided with at least one exit opening 32 for compressed air 33 (FIG. 1, FIG. 2,), which is focused onto the folding table 6 and/or onto the top side 2.sub.1 . . . n of the printed sheet 2.sub.1 . . . n to be positioned on the folding table 6. To brake the printed sheet 2.sub.1 . . . n approximately at the same time as pressing down the back edge 2.sub.1 . . . n, the pressing-down mechanisms 29 are provided with a mechanical braking element 34 for this printed sheet 2.sub.1 . . . n, which is arranged between the at least one first exit opening 32 for compressed air 33 and the folding table 6 and acts in the region of the back edge 2.sub.1 . . . n onto the top side 2.sub.1 . . . n of the printed sheet 2.sub.1 . . . n to be positioned on the folding table 6. Depending on the requirement, only a single pressing-down mechanism 29 can also be used which is then arranged centrally, as seen in the direction transverse to the conveying direction 4, meaning essentially in the vertical plane through the folding sword 7.

[0046] The apparatus 1 comprises a machine control 35 which is operatively connected to the folding sword 7 and the pressing-down mechanisms 29. To activate the folding sword 7 and the pressing-down mechanisms 29, corresponding control lines 36 with magnetic valves 37 are provided. At least one sensor 38 that is operatively connected to the machine control 35 is arranged in the region of the conveyor 3 for detecting the printed sheets 2.sub.1 . . . n transported with the conveyor 3. The sensor 38 is connected for this to the machine control 35 via a data line 39.

[0047] FIG. 2 shows a simplified, schematic view from the front of the apparatus 1 according to FIG. 1, shown counter to the conveying direction 4 for the printed sheets 2.sub.1 . . . n. In particular shown herein are the holding element 7 for the folding sword 7, the individual belt sections of the lower belt 11 on the conveyor 3, which are embedded in the folding table 6, the gap width 25 of the folding roller gap 25, as well as the side distance 30 for the respective pressing-down mechanism 29, relative to the compressed-air device 15 on the folding sword 7.

[0048] During the operation of the apparatus 1, the front edge 2.sub.1 . . . n of a following printed sheet 2.sub.1 . . . n, meaning in FIG. 1 the printed sheet 24, is supplied while raised as compared to the back edge 2.sub.1 . . . n of the printed sheet 2.sub.1 . . . n positioned on the folding table 6, meaning in FIG. 1 the printed sheet 23. This can be achieved with a fixed or adjustable section 40 in the lower belt 11 (FIG. 1, FIG. 2), shown herein, with the aid of an active element that is not shown or a ramp which is also not shown, for lifting up the front edge 2.sub.1 . . . n of the following printed sheet 2.sub.1 . . . n as compared to the back edge 2.sub.1 . . . n of the printed sheet 2.sub.1 . . . n positioned on the folding table 6.

[0049] Once a number of printed sheets 2.sub.1 . . . n is gathered on the folding table 6 that forms the gathering device 6, meaning they have been deposited thereon to form a stack 41, this stack 41 is subsequently folded with the aid of the folding sword 7 and the folding roller pair 8, and a folded print product 41 is created (FIG. 3).

[0050] For this, the corresponding magnetic valves 37 of the folding sword 7 are initially opened with the machine control 35. Compressed air 16 then streams from the first compressed-air source 14 into the segments 17 of the compressed-air line 15. Coming from the outlet openings 18 of the segments 17, this compressed air 16 impinges on the stack 41, respectively the top side 2.sub.1 . . . n of the upper printed sheet 2.sub.1 . . . n, and is focused in such a way that the stack 41 is pushed through the recess 6 in the folding table 6 and between the individual belt sections of the lower belt 11 into the folding roller gap 25 of the folding roller pair 8 and is finally folded with the aid of the folding rollers 9, 10. The impulse for opening the magnetic valves 37 and thus for folding the stack 41 is triggered only if the following printed sheet 2.sub.1 . . . n has an overlap 42 (FIG. 1), as compared to the stack 41 resting on the folding table 6. On the one hand, this prevents a blocking of the feeding of the following printed sheet 2.sub.1 . . . n into the clearance space between the stack 41 and the upper belt 12 when the stack 41 moves between the folding rollers 9, 10. On the other hand, the following printed sheet 2.sub.1 . . . n functions as a guide for the ends of the printed sheet 2.sub.1 . . . n of the stack 41 to be formed, which pass last through the folding rollers 9, 10. This avoids the forming of so-called dog ears, meaning where the ends are turned over in vertical direction because of the relatively high acceleration during the transport and are then bent over by the folding rollers 9, 10. The length for the overlapping 42 here is about 1 to 20% of the length of a printed sheet 2.sub.1 . . . n in the stack 41.

[0051] Owing to the fact that the compressed-air device 15 for the folding sword 7 is divided into several segments 17, it is possible to admit only those segments 17 with compressed air 16 which are necessary for the corresponding format folding the printed sheets 2.sub.1 . . . n and/or forming the stacks 41, meaning the segments 17 arranged in the region of stack 41. The segments 17 not needed and arranged outside of this region remain closed through non-activation of their magnetic valves 37. On the one hand, this saves compressed air 16 while, on the other hand, unused compressed air is prevented from entering the clearance space between the folding sword 7 and the stack 41 to be folded where it may result in eddying and hinder the concrete orientation of the upper printed sheet 2.sub.1 . . . n in the stack 41.

[0052] The print product 41 that is produced through folding of the stack 41 is transported further to an intermediate storage location or to the post-processing via a transport device 44 that adjoins the folding roller pair 8 and consists, for example, of individual belt sections 43. If only the end stop 19 is adapted to the format of the printed sheets 2.sub.1 . . . n which form a joint stack 41, the print product 41 is conveyed away off-center on the transport device 43, as shown in FIG. 3. On the other hand, if in addition to the end stop 19 the segment 40 and the pressing-down mechanisms 29 are moved in or counter to the conveying direction 4, the print product 41 can still be centrally transported on the transport device 43.

[0053] If printed sheets 2.sub.1 . . . n having a larger or smaller format as compared to the current work order are to be processed with the apparatus 1, the end stop 19 can be moved via the first adjusting device 20 either in or counter to the conveying direction 4, so that these printed sheets 2.sub.1 . . . n are also deposited successively one above the other on the folding table 6, functioning as gathering device 6, and a stack 41 is formed with these printed sheets 2.sub.1 . . . n. In addition, a corresponding adjustment of the step 40 and the pressing-down mechanism 29 in or counter to the conveying direction 4 can also take place.

[0054] As a result of the height-adjustable arrangement of the folding sword 7 on the holding element 7, the vertical distance between the folding sword 7 and the folding table 6 can correspondingly be adjusted for a following work order with different thicknesses for the stack 41 of printed sheets 2.sub.1 . . . n to be folded. As a result, it is advantageously possible to adapt this vertical distance to the number of printed sheets to be folded and also to the type of paper used.

[0055] Since the stack forming occurs prior to the folding with this apparatus 1, the transport speed for the printed sheets 2.sub.1 . . . n in the stack 41 can be reduced easily and cost-effectively as compared to the individually folded sheets according to the prior art. Depending on the post-processing machines used upstream of the apparatus 1, a lower number of cycles can thus be realized, which permits a more careful further processing while avoiding quality problems. Owing to the easy way of supplying previously non-folded printed sheets 2.sub.1 . . . n to the folding table 6, the number of blank pages in the stack 41 and thus in the print product 41 can be reduced easily, as compared to the known prior art, without increasing the transport speed. As a result, quality problems can be avoided in the machines used for the further processing.

[0056] FIG. 3 shows a second exemplary embodiment of an inventive apparatus 1 for which the lower belt 11 and the upper belt 12 of the conveyor 3 respectively have two transport belt sections 11, 11, 12, 12 which are successively arranged in conveying direction 4, wherein more than two transport belt sections 11, 11, 12, 12 can also be arranged. As a result, the folding table 6, the folding sword 7 and the folding roller pair 8 of the apparatus 1 can advantageously be separated from the conveyor 3, meaning from the feeding of the printed sheets 2.sub.1 . . . n.

[0057] In contrast to the first exemplary embodiment, the compressed-air device 15 here is not embodied segmented, and the apparatus 1 can thus be produced even easier and more cost-effective. In the same way as the compressed-air device 15, the pressing-down mechanisms 29 here are also connected to the first compressed-air source 14, so that no second compressed-air source is advantageously needed. The upper belt 12 furthermore converges toward the lower belt 11 in the region of the folding table 6, meaning it is embodied with a converging conveying gap 13 in conveying direction 4, which additionally supports the guidance of the printed sheets 2.sub.1 . . . n in the region of the folding table. Of course, the lower belt 11 can also converge toward the upper belt 12 or both belts 11, 12 can converge toward each other.

[0058] Also conceivable are inventive apparatuses and corresponding methods for which the different features of the first and second exemplary embodiment are combined in different ways.

[0059] It will be understood that the above description of the present invention is susceptible to various modifications, changes and adaptations, and that the same are intended to be comprehended within the meaning and range of equivalents of the appended claims.